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Abstract- In this paper, it is shown how to use the recently developed Firefly Algorithm to optimize abrasive water-jet cutting as a nonlinear multi-parameter process. Back propagation neural network were developed to predict surface roughness in abrasive water-jet cutting (AWJ) process. In the development of predictive models, machining parameters of traverse speed, water-jet pressure, standoff distance and abrasive flow rate were considered as model variables. Firefly Algorithm by using back propagation neural network optimizes glass surface roughness in abrasive water-jet cutting and proposes appropriate parameters for minimum surface roughness. Testing results demonstrate that the model is suitable for predicting the response parameters. However this algorithm has not be tested for practical problems, the results showed this algorithm applicable for processes with complex nature.

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Point based 3D modeling has recently received greater attention, mainly due to its simplicity. One of the most fundamental operations for point set processing is to find the neighbors of each point in point clouds. This paper presents a new method called homogeneous neighborhood for determining neighbors in point clouds. This method of choosing neighbors, in addition to the distance takes into consideration the directional balance by improving the k nearest neighbors. The directional balance describes whether the neighbors are well spread around the point of concern. In this study effects of selecting neighbors on normal vector estimation are investigated. Normal vector is calculated using homogeneous neighborhood. For evaluation of the proposed method in determining neighbors, normal vector are calculated using the k nearest neighbors. The results show that the homogeneous neighborhood method is more accurate in normal vector estimation than the k nearest method. For evaluation of the homogeneous neighborhood method, it was employed in point cloud registration application. The results of registration by using the homogeneous neighborhood show that this method of neighbor selection yields reduced registration errors.

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Abrasive water jet cutting process can produce tapered edges on cutting kerf. This problem can limit the applications of abrasive water jet cutting process and in some cases it is necessary another edge preparation process. In this paper, an experimental investigation kerf characteristics of Ti-6Al-4V titanium alloy under abrasive water jet cutting is presented. In this regards, it is shown how to use the hybrid approach of Taguchi method and principal component analysis to optimize abrasive water jet cutting are used in this paper. The abrasive water jet cutting process input parameters effect on material removal rate and the characteristics of the surface. A considerable effort was made in understanding the influence of the system operational process parameters such as water jet pressure, traverse speed, abrasive flow rate, and standoff distance. Due to appropriate selecting abrasive water jet cutting process parameters leads to optimizing of kerf characteristics include top kerf width, kerf tapper and kerf deviation, therefore it is important to select appropriate input parameters. The obtained results from this method show that the hybrid approach of Taguchi method and principal component analysis is a suitable solution for optimizing of abrasive water jet cutting process.

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With the rapid development of 3D laser scanners, point-based discrete shape modeling is being widely used in many engineering applications, e.g. quality control, reverse engineering, computer graphics and machine vision. Point cloud discrete curvature estimation is considered basic operation in point cloud operations and is used in many applications related to cloud points. This paper presents a novel method for point clouds surface curvature estimation. One of the key components of point clouds surface curvature calculation is neighbor coordinates of query point. For selecting neighbors homogeneous neighborhood method is used. This method of choosing neighbors, in addition to the distance takes into consideration the directional balance by improving the k nearest neighbors. Surface normal vector is estimated by neighbors coordinates. In this paper surface curvature is calculated based on normal vector and homogeneous neighbors coordinates. Surface curvature calculated using the novel method is called umbrella curvature. To evaluate how this method performs, umbrella curvature values are calculated for a number of cloud points and the results are used in some different applications. The results show that the proposed method performs well in point clouds curvature estimation.

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Registration of point clouds is a key process in creating a digital model in reverse engineering. Registration is complex and ill-conditioned problem and these impede to achieve fully automatic comprehensive algorithm.in this study a new method to improve automation level is proposed. In this method, at first surface features are extracted from point clouds and then these data use for detecting correspondence points between point clouds. Registration process accuracy depends on carefully selected corresponding point between point clouds. In present research surface curvature and local shape are used for finding correct correspondence points. For feature extraction, surface curvature for each point of point clouds is calculated by using umbrella curvature and also a new method for determining local shape is presented. For each point of point cloud a shape number is determined. Determination of shape number is done by neighbors’ coordinates of point of concern. In this method, the corrected corresponding points are points that have almost equal umbrella curvature and shape number. Rigidity helps algorithm to find pairwise points. Analyzing results shows that the proposed algorithm performs well and has appropriate abilities on fully automatic registration of point clouds.

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abrasive water jet is one of the most popular cutting methods today due to its ability and unique features such as the ability to cut complex shapes as well as the wide range of materials and non - creation of thermal distortion at the cutting site. The accuracy of the process is mainly due to selecting the cutting parameters. The sheet used in this study is aluminum 7075 with a thickness of 25 mm. In this research, for water jet pressure, forward speed and nozzle distance to the surface of the workpiece, three surfaces and for the impingement angle of two surfaces were considered. In order to investigate the quality of the cut - off area, the effect of process parameters on the high and low width of the cut section and also the cut - surface slope is investigated. Finally, the cut gap created by this process has special geometrical features that in some cases is the limitation of the process. The results showed that the change in the direction of the water jet from the perpendicular to the surface of the work piece, although the width of the cutting crack cannot be changed, the surface quality decreases and the cutting surface slope increases.